can someone please help

Discussion in 'Stability' started by stlamont, Jan 8, 2017.

  1. stlamont
    Joined: Jan 2017
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    Location: Kingston Jamaica

    stlamont New Member

    1. Need urgent help in how to calculate total cargo weight a ship carry.

    2. A ship is expected to sail a distance of 3,200 n.m. at an average speed of 12

    knots. Calculate her expected time of arrival if she departed on December 28,

    2014 at 2200 hours.
  2. Olav
    Joined: Dec 2003
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    Location: Filia pulchra Lubecæ

    Olav naval architect


    Payload = Total displacement - light ship weight - provisions (fuel, lube oil, food,...) - ballast water


    Distance travelled: 3200 nm
    Avg. speed: 12 kts = 12 nm/h

    --> Time en route: 3200 nm/(12 kts * 24 h) = 11.11111 d.

    Since 2014 was no leap year, the time of arrival is on

    March 11th, 2014 (Feb 28th + 11 d), at 0.11111 d - 2 h (remaining two hours from Feb. 28th), thus at 0:40 in the morning (assuming the vessel stays within one time zone).

    Was this your homework, stlamont? :D
  3. Heimfried
    Joined: Apr 2015
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    Heimfried Senior Member

    No, no, the homework is: doublecheck the results of your friendly helper.
  4. Olav
    Joined: Dec 2003
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    Olav naval architect

    Oops! :eek:

    Correction: January 8th, 2015 at 0040.

    Don't know why I read February instead of December... :confused:
  5. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Question 1 looks tricky to me !

  6. kilocharlie2
    Joined: Nov 2016
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    kilocharlie2 Junior Member

    Compliments to Olav, who makes the answers seem simple!

    Question 1 involves a technique known to mathematicians as subtraction. Question 2 involves a method known as division.

    Of course it leaves out choice of route, time of year, winds, current, coriolis effect, and error.

    On the ocean, we do not plow through distance, we plow through moving water and wind. It's a blasted good ship design that makes 12 knot in all weather and current, and a phenomenal skipper who stays on course around 1/8th of the planet, although our GPS / computer combo is making solid inroads into this last part.
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